PHP became a monk halfway (1)_PHP tutorial

Finally the environment is configured, try PHP!

Where should I write the code?

code

Mark the author and make comments? //author : matter

/*

*author : matter

*/

#author : matter

It finally officially started, ok, let’s go directly to the classic case

Pay attention to the discolored parts

Single quotes are OK, double quotes are also OK Single quotes have incomplete support for escape characters! Echo can be used, print can be used, and printf can also be used Why do you add parentheses to printf? The brackets for echo() and print() can be omitted Is there a difference between echo and print? echo() has no return value, print() successfully outputs and returns 1 So it can be seen that echo() is faster than print()! Use printf for dynamic text, and echo for static text. $test=sprintf("$%.2f",12.3424);

printf("Goodbye-- World,$test");

sprintf can assign values to variables~

It’s time to show me variables! Weakly typed language --- Everything is scalar

$myVar = "anything";

Array

$arr[0] = "abc";

It’s time to meet your partner! class MyTest {

private $a;

public function getA() {

return $this->a;

}

public function setA($a) {

$this->a = $a;

}

$useage = new MyTest();

$useage->setA("HI~");

echo $useage->getA();

My own experience with JAVA

Function has no return type Use "->" instead of "." to call methods and properties Regardless of whether it has been declared or not, always add $ in front of the variable.

I don’t know what type the variable is... What should I do? Cast

(array)$sth

Automatic conversion

When calculating a string, take the previous number The judgment condition of If() judges whether the calculation result is non-0

I want to have the right to know and control the variable type! String Gettype( mixed var ); Return the type of variable var

Boolean settype( mixed var , string type ) Convert the type of variable

How big a part is the variable responsible for? GLOBAL $var; //Global variable STATIC $var; //Static variable At present, only the keywords are different, the rest is normal

Super global variables---predefined, related to the environment $_SERVER , $_GET , $_POST , $_COOKIE

$_FILES , $_ENV

When the variable remains unchanged~ Define("PI" , 3.1415);

Operator, operand, control statement New:AND OR NOT XOR

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